pahole: Improve error message when not resolving symbolic names in filters

To improve figuring out why this command line fails:

  $ pahole -F dwarf -V ~/bin/perf --header=perf_file_header --seek_bytes '$header.data.offset' --size_bytes='$header.data.size' -C 'perf_event_header(sizeof,type,type_enum=perf_event_type,filter=type==PERF_RECORD_MMAP2)' --prettify perf.data
  pahole: sizeof_operator for 'perf_event_header' is 'size'
  pahole: type member for 'perf_event_header' is 'type'
  pahole: type enum for 'perf_event_header' is 'perf_event_type'
  pahole: filter for 'perf_event_header' is 'type==PERF_RECORD_MMAP2'
  Symbolic right operand in 'type==PERF_RECORD_MMAP2' but no way to resolve it to a number (type_enum empty or hasn't found any so far) at CU 'builtin-annotate.c')
  pahole: invalid filter 'type==PERF_RECORD_MMAP2' for 'perf_event_header'
  pahole: type 'perf_event_header' not found or arguments not validated
  $

In this case we don't have the 'enum perf_event_header' in
builtin-annotate.o, so we must defer trying to parse that
perf_event_header(sizeof,type,type_enum=perf_event_type,filter=type==PERF_RECORD_MMAP2)
class expression to when we find it.

When using BTF it all works as all types are in just one CU:

  $ pahole -F btf -V ~/bin/perf --header=perf_file_header --seek_bytes '$header.data.offset' --size_bytes='$header.data.size' -C 'perf_event_header(sizeof,type,type_enum=perf_event_type,filter=type==PERF_RECORD_MMAP2)' --prettify perf.data
  pahole: sizeof_operator for 'perf_event_header' is 'size'
  pahole: type member for 'perf_event_header' is 'type'
  pahole: type enum for 'perf_event_header' is 'perf_event_type'
  pahole: filter for 'perf_event_header' is 'type==PERF_RECORD_MMAP2'
  pahole: seek bytes evaluated from --seek_bytes=$header.data.offset is 0x3f0
  pahole: size bytes evaluated from --size_bytes=$header.data.size is 0xd10
  // type=perf_event_header, offset=0xc20, sizeof=8, real_sizeof=112
  {
  	.header = {
  		.type = PERF_RECORD_MMAP2,
  		.misc = 2,
  		.size = 112,
  	},
  	.pid = 1533617,
  	.tid = 1533617,
  	.start = 94667542700032,
  	.len = 90112,
  	.pgoff = 16384,{
  		.maj = 0,
  		.min = 33,
  		.ino = 35914923,
  		.ino_generation = 26870,
  	},{
  		.build_id_size = 0,
  		.__reserved_1 = 0,
  		.__reserved_2 = 0,
  		.build_id = { 33, 0, 0, 0, -85, 4, 36, 2, 0, 0, 0, 0, -10, 104, 0, 0, 0, 0, 0, 0 },
  	},
  	.prot = 5,
  	.flags = 2,
  	.filename = "/usr/bin/ls",
  },
  // type=perf_event_header, offset=0xc90, sizeof=8, real_sizeof=128
  {
  	.header = {
  		.type = PERF_RECORD_MMAP2,
  		.misc = 2,
  		.size = 128,
  	},
  	.pid = 1533617,
  	.tid = 1533617,
  	.start = 140033104936960,
  	.len = 159744,
  	.pgoff = 4096,{
  		.maj = 0,
  		.min = 33,
  		.ino = 35909039,
  		.ino_generation = 26870,
  	},{
  		.build_id_size = 0,
  		.__reserved_1 = 0,
  		.__reserved_2 = 0,
  		.build_id = { 33, 0, 0, 0, -81, -19, 35, 2, 0, 0, 0, 0, -10, 104, 0, 0, 0, 0, 0, 0 },
  	},
  	.prot = 5,
  	.flags = 2,
  	.filename = "/usr/lib64/ld-linux-x86-64.so.2",
  },
  <SNIP more PERF_RECORD_MMAP2 records>
  $

  $ pahole --contains_enumerator PERF_RECORD_MMAP2
  enum perf_event_type {
  	PERF_RECORD_MMAP             = 1,
  	PERF_RECORD_LOST             = 2,
  	PERF_RECORD_COMM             = 3,
  	PERF_RECORD_EXIT             = 4,
  	PERF_RECORD_THROTTLE         = 5,
  	PERF_RECORD_UNTHROTTLE       = 6,
  	PERF_RECORD_FORK             = 7,
  	PERF_RECORD_READ             = 8,
  	PERF_RECORD_SAMPLE           = 9,
  	PERF_RECORD_MMAP2            = 10,
  	PERF_RECORD_AUX              = 11,
  	PERF_RECORD_ITRACE_START     = 12,
  	PERF_RECORD_LOST_SAMPLES     = 13,
  	PERF_RECORD_SWITCH           = 14,
  	PERF_RECORD_SWITCH_CPU_WIDE  = 15,
  	PERF_RECORD_NAMESPACES       = 16,
  	PERF_RECORD_KSYMBOL          = 17,
  	PERF_RECORD_BPF_EVENT        = 18,
  	PERF_RECORD_CGROUP           = 19,
  	PERF_RECORD_TEXT_POKE        = 20,
  	PERF_RECORD_AUX_OUTPUT_HW_ID = 21,
  	PERF_RECORD_MAX              = 22,
  }
  $

If we replace PERF_RECORD_MMAP2 with its numeric value, then it works
with DWARF as well.

  $ pahole -F dwarf -V ~/bin/perf --header=perf_file_header --seek_bytes '$header.data.offset' --size_bytes='$header.data.size' -C 'perf_event_header(sizeof,type,type_enum=perf_event_type,filter=type==10)' --prettify perf.data --count 1
  pahole: sizeof_operator for 'perf_event_header' is 'size'
  pahole: type member for 'perf_event_header' is 'type'
  pahole: type enum for 'perf_event_header' is 'perf_event_type'
  pahole: filter for 'perf_event_header' is 'type==10'
  pahole: seek bytes evaluated from --seek_bytes=$header.data.offset is 0x3f0
  pahole: size bytes evaluated from --size_bytes=$header.data.size is 0xd10
  // type=perf_event_header, offset=0xc20, sizeof=8, real_sizeof=112
  {
  	.header = {
  		.type = PERF_RECORD_MMAP2,
  		.misc = 2,
  		.size = 112,
  	},
  	.pid = 1533617,
  	.tid = 1533617,
  	.start = 94667542700032,
  	.len = 90112,
  	.pgoff = 16384,{
  		.maj = 0,
  		.min = 33,
  		.ino = 35914923,
  		.ino_generation = 26870,
  	},{
  		.build_id_size = 0,
  		.__reserved_1 = 0,
  		.__reserved_2 = 0,
  		.build_id = { 33, 0, 0, 0, -85, 4, 36, 2, 0, 0, 0, 0, -10, 104, 0, 0, 0, 0, 0, 0 },
  	},
  	.prot = 5,
  	.flags = 2,
  	.filename = "/usr/bin/ls",
  },
  $

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 14 insertions, 6 deletions

diff --git a/pahole.c b/pahole.c
index 1a7f7eb8..bb68d40b 100644
--- a/pahole.c
+++ b/pahole.c
@@ -2839,7 +2839,7 @@ out:
 	return printed;
 }
 
-static int class_member_filter__parse(struct class_member_filter *filter, struct type *type, char *sfilter)
+static int class_member_filter__parse(struct class_member_filter *filter, struct type *type, const struct cu *cu, char *sfilter)
 {
 	const char *member_name = sfilter;
 	char *sep = strstr(sfilter, "==");
@@ -2888,9 +2888,17 @@ static int class_member_filter__parse(struct class_member_filter *filter, struct
 
 	// If t he filter member is the 'type=' one:
 
-	if (list_empty(&type->type_enum) || type->type_member != filter->left) {
+	if (list_empty(&type->type_enum)) {
+		if (global_verbose) {
+			fprintf(stderr, "Symbolic right operand in '%s' but no way to resolve it to a number (type_enum empty or hasn't found any so far) at CU '%s')\n",
+				sfilter, cu->name);
+		}
+		return -1;
+	}
+
+	if (type->type_member != filter->left) {
 		if (global_verbose)
-			fprintf(stderr, "Symbolic right operand in '%s' but no way to resolve it to a number (type= + type_enum= so far)\n", sfilter);
+			fprintf(stderr, "type->type_member (%p) != filter->left (%p)\n", type->type_member, filter->left);
 		return -1;
 	}
 
@@ -2910,11 +2918,11 @@ static int class_member_filter__parse(struct class_member_filter *filter, struct
 	return 0;
 }
 
-static struct class_member_filter *class_member_filter__new(struct type *type, char *sfilter)
+static struct class_member_filter *class_member_filter__new(struct type *type, const struct cu *cu, char *sfilter)
 {
 	struct class_member_filter *filter = zalloc(sizeof(*filter));
 
-	if (filter && class_member_filter__parse(filter, type, sfilter)) {
+	if (filter && class_member_filter__parse(filter, type, cu, sfilter)) {
 		free(filter);
 		filter = NULL;
 	}
@@ -3394,7 +3402,7 @@ out_btf:
 		}
 
 		if (prototype->filter) {
-			type->filter = class_member_filter__new(type, prototype->filter);
+			type->filter = class_member_filter__new(type, cu, prototype->filter);
 			if (type->filter == NULL) {
 				fprintf(stderr, "pahole: invalid filter '%s' for '%s'\n",
 					prototype->filter, prototype->name);